Process of treating materials.



UNITED STAClTEi PATENT OFFICE.

FItEDERICK W. YOST, OF CHICAGO, ILLINOIS.

PROCESS OF TREATING MATERIALS.

1 ,oolansa.

Specification of Letters Patent. Patented Sept. 19, 1911.

No Drawing. Application filed September 4, 1909, Serial No. 516,305. Renewed January 16, 1911. Serial To all whom it may concern:

Be it known that I, FREDERICK \V. Yosr, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Processes of Treating Materials, of which the following is a specification.

My invention relates to the treatment of materials; and it comprises a process wherein a reaction-producing gas is conducted through the interiorof a mass of material and by its aid one reaction is propagated through the mass toward the surface of gas entrance and'another reaction is propagated.

through the mass toward the surface of gas exit; and it comprises more particularly, but not. exclusively, the calcining, roasting, or reducing and clinkering of finely divided material in a stationary or movable mass; all as more fully hereinafter setiforth and as claimed.

One of the chief objects attained by my invention is the high efficiency of the process, because the gaseous element is brought to the zones of reaction uncontaminated by the products of reaction, since the react-ionsupporting gas is conducted through the material toward the surface of initial re action. And since the waste products of reaction are not conducted through the'untreated material both reactions are susceptible of full control, because the untreated material is acted upon only by the energy developed at the zone'of initial reaction.

Another important object attained is the lengthened life of any apparatus employed,

because in my process the volatile products escape from the interior of the mass at the same surface at whlch the first reaction is initiated; therefore, the destructive agencies in well known forms ofchain grate stoker furnaces.

My process may be used for clinkering finely divided oxid ores. Such material may be in a finely divided state as found in nature, or it may be finely divided as the result of treatment by concentration, or it may be a finely subdivided metallurgical waste such as blast furnace fine dust. The finely,

through the mass to the lower surfacepf the charge; when the zone of combustion reaches the lower surface of the charge a clinker-ing reaction is propagated upward through the mass, from the lower to the 11 per surface, by the continued blowing of air through the charge; and the volatile products of combustion escape at the upper surface and join the furnace gases. When my process is carried on in a' reverberatory furnace, provided with a'fixed perforated hearth, the heat is first propagated downward through the charge and the clinker-- ing reaction follows [the conclusion of the heating stage. \Vhen the material is clinkered in a chain grate stoker furnace the various stages of the process take place simultaneously, one portion of the charge being heated while another portion of the charge is being clinkered. It will be evident that' an important feature in the economy of the treatment is in maintaining, 1n the ulterior of the charge, the least degree of reductionthat will initiate the agglomerating reaction and this condition necessitates the use of the minimum amount of combustible material in the charge. The carbonaceous component in the charge may be still further reduced in quantity by adding combustible gas to' the air, conducted through the mass, or by substituting hot air for cold air. When it is desired to produce clinker containing the lower oxids of more or less reduced metal it will be necessary to maintain, in the interior charge.

amount of sulfur, found in ores and concen.

of the charge, conditions that are more highlyreducing than those required for the production of high oxid clinker. Such highly reducing conditions may be secured by the use of larger proportions of-carbonaceous material in the charge; or by the addition of combustible gas to the air used for the propagation of both reactions; or by the use of air for the propagation of the initial reaction and combustible gas for the propagation of the second reaction. The finished product may be made into large and relatively dense blocksof clinker, such as are desirable for open hearth furnace use, or into highly porous and relatively small pieces of clinker, such as are desirable for blast furnace use, by varying the amount of air blown through the charge during the progress of and after the completion of the clinkering reaction. I

My process may also be used for roasting and clinkering finely divided sulfid ores, concentrates or flue dust. The finely divided ore is charged intoany suitable appa ratus; air is introduced at the lower surface of the charge and is conducted upward through the interior of the mass; the opposite surface of the charge is ignited and the heat is propagated downward by internal combustion; when the plane of ignition reaches the lower surface, the clinkering reaction is propagated upward, from the lower to the upper surface, by the continued blowing of the air through the charge; and I the volatile products of combustion escape at the upper surface. If there is'suflicient sulfur .in the material for self-supporting combustion, after ignition, the process can be carried onin an open top receptacle; if there is'not suflicient sulfur to support combustion, after ignition, the process may be carried on ma reverberatory furnace with a perforated hearth, or in a suitable form of chain grate Stoker furnace, where a. moving body of hot gases, generated by the com'bus tion of extraneous fuel, can be maintained in contact with the upper surface of the Material containing the maximum trates, may be treated in one of the types. of furnacereferred to without the use of an igniting flame generated from the combustion of extraneous fuel; because, when the brickwork of the furnace has once been heated to a high temperature, the radiated heat will ignite the sulfur of the ore and the combustion of the sulfurwill-maintain the temperature of' the hot brickwork; therefore, the waste gases, escaping from the charge, may be used for sulfuric acid manufacture or other' by-product purpose.

WVhen the sulfur in the charge is too low for self-ignition and when, nevertheless, it is desirable to use the waste sulfur gases for byproduct purposes, the heat from the combus-- USE.

tion of extraneous fuel maybe transmitted nated by the products of reaction, hence the air acts with greatcfliciency and only the minimum volume need be used therefore, the waste sulfur gases are highly concentrated and are very' valuable forby-product lVhere the material is too low in sulfur for the propagation of internal combustion it will be necessary to add other combustible elements to the charge. The heating and clinkering functions are divided into separate stages, each of which is subject to independent control, thus making it possible to produce at will clinker of either high or low sulfur content to suit the requirements of the subsequent smelting operation.

My process is also well adapted for the clinkering of cement materials. The finely ground raw mix is intimately mixed with finely divided carbonaceous material and is charged into one of the types of furnace referred to. The upper surface of the charge is heated by contact with the moving body of hot furnace gases, generated by the combustion of extraneous fuel, air is introduced at the lower surface of the charge and is conducted upward through the interior of the mass; the heat, applied to the upper surface, is conducted downward through the mass by internal combustion from the upper to the lower surface; when the plane of combustion reaches the lowerSurface the clink cring reaction is propagated upward, from the lower. to the upper surface, by the continued blowing of air through theinterior of the mass; and the volatile products and gases formed. from the components of the charge escape at the upper surface and join the furnace gases. charge are decomposed during the first or heating stage of the process and the clinker isformed during, the second stage. termixed fuel in any region is consumed by the internal reaction only when the hot combustion zone, in its initial and downward progress, or in its second and upward prog ress, reaches that region; therefore, the -small particles of fuel release their heat only at the time-and at the place when and where it is needed; Small clinker with a highly porous structure is more readily crushed and ground into finished cement than is dense clinker of large size, and this desirable physical quality maybe obtained by a suitable variation the amount er air conducted through the charge during the progress of and after-the completion of the clinkering reaction.-

In the treatment of any' ofthe materials described in these examples various modifr The carbonates of. the

The inditional air conducted through t e charge ulated,'or the character of the reaction may be varied, by the addition of steam, volatile products of combustion or other modifying elements to the air-conducted through the interior of the mass. \Vhen the material to be clinkered is of a highly refractory nature it may be desirable to add a flux to lower the clinkeringtemperature whereby the fuel.

consumption may be lessened. The combustible components of the charge may be lessened in amount, or wholly eliminated, by the use of highly heated air conducted through the mass with or without an ad-' mixture of combustible gases. Where the ash from the combustion of solid fuel is an undesirable ingredient of the clinkered product liquid or semi-liquid fuel may be used as the heat developing component of the charge. 7

This process requires that the conditions relating to the composition of the charge, the composition and temperature of the 1gniting or heating gases, and the composition, temperature .and pressure of the combustion-supporting' gas, be properly correlated, so'that a heating zone unaccompanied by a clinkering reactiongwill be propagated downward through .the charge to the lower surface during the first stage of the process, and so that during the second sta e the adand acting upon the heated material, will initiate a clinkering reaction at the lower surface and will aid in propagating this clinkering reaction upward through the charge to the upper surface. During the first stage of the present process, the charge must be maintainedin a loose, granular conditiomso that the material of the charge can be prop- -erl v calcined, roasted or otherwise treated before it is clinkered; and in this respect, the present process differs essentially from that described in my co-pending application, Serial'No. 516,306, filed Se tember 4, 1909, (renewed Jan. 16, 1911, erial No.

602,980) wherein there must be such a change of correlations of the controllable conditions that during the first stage a clinkering reaction will be initiated at the upper surface, and will be propagated downward through the upper portion of the charge, coincidentally with the heating of the charge from the upper to the lower surface; and that, during the second stage a.

clinkering reaction will also be initiated at the lower surface,' and will be propagated upward throughthe unclinkered portion of the charge. I do not wish to be limitedto treatment of the specific materials described in the ex amples, nor do I wish to be limited to the specific details of treatment there described, nor merely to the specific process of treating iron oxids as herein described, since it will be evident to those skilled in the art that this invention applies to the treatment of any material, or any mixture of materials, of such a nature that an initial reaction can be propagated through a mass in one direction, and a second reaction can be propagated through the mass in another direction, by the means described. It will be further evident that the kinds of treatment accorded the material are not limited to calcining, roasting, or reducing and clinkering, but may include any treatment which can be carried on in separate stages, as described. It will be also evident that the gaseous element can vary widely as to composition, and may be either an oxidizing or reducing agent, provided, that under suitable control of conditions, it has the property of aiding in propagating one reaction toward the surface of gas entrance and another reaction toward the surface of gas exit. Neither do I wish to be limited to the use of one 'kind of gas for the propagation of,both reactions, since it will be evident that for some purposes it may be desirable to use an oxidizing gas to propagate one reaction and a reducin gas to propagate the other reaction. In al of the examples, I- have described a: downward propagation of theinitial reaction and an upward course for the reaction-sup )orting gas; but for dif-' ferent conditions, I may prefer to propagate the initial reaction upward, or in any other direction, )rovided the gaseous element is conducted in a direction other than the course of initial reaction. I also have described, in the examples, conditions which result in the formation of volatile products of reaction, but it will be evident that nonwhen the reactions are of such a character that the gaseous element, conducted through the interior of the mass, is absorbed by the material of the charge.

It is to be understood that the words, finely divided, as herein used, have reference to any degree of subdivision that best adapts the material to treatment by my process, as some materials respond to treatment better when in a relatively coarse condition while other materials respond to treatment only when in a finely divided state. It is to be also understood that, where the material is described in the claims as containing various components, the various components may be originally contained in the material, or they may be added to the material to prepare it for treatment.

In my co-pendin application, Serial Number 516,306, file Se tember 4th, 1909, (renewed Jan. 16, 1911, erial No. 602,980)

I have described and claimed a specific embodiment of this invention wherein, by

proper control of thermal and other conditions, one clinkering reaction proceeds through the mass in a direction other than the course of the gas current and another clinker-ing reaction proceedsin a different direction, and this specific embodiment of my invention I do not claim herein; inthe embodiment which is specifically claimed in the present application, the clinkering reaction proceeds through the mass in one direction only. I i

lVhat I claim is:

material capable of undergoing propagative reaction, which comprises initiating a propaga'tive reaction at a surface of a mass of the material, transmitting a current of reaction-supporting gas toward the surface of initial reaction, causing the initial reaction to travel through the mass in a direction other than the flow of the reaction-support ing gas, and propagating a second reaction through the mass toward the surface of initial reaction, substantially as described.

2. The process of treating finely divided material containing heat developing components, which comprises initiating a reaction in a region of a mass of the mate- 'rial, conducting a reaction-supporting gas through the mass toward the region of initial reaction, propagating the initial reaction through the mass in a direction other than the flow of the reactioirsupporting gas,

and propagating a second reaction through the mass in the direction of flow of the reaction-supporting scribed.

3. The process of treating finely divided material containing heat developing components, which comprises initiating a reaction at a surface of a mass of the material,

introducing a reaction-supporting gas at an-.

other, surface of the mass, conducting the reactlon-supportlng gas through the mass,

propagating the initial reaction through the mass in one direction, and propagating a second reaction through the mass in another -direction, substantially as described.

4. The process of treating finely divided material containing gas forming components, which comprises initiating a reaction in aregion of a mass of the material, conducting a reaction-supporting gas throughthe mass toward. the region of initial reaction, propagating the initial reaction through the mass in a direction other than the flow of the reaction-supporting gas, and

50 propagating a second reaction through the.

mass in the direction of flow of the reactionsupporting gas, substantially as described.

5. The process of treating finely divided material containing gas forming components, which comprises initiating a reaction 1. The process of treating finely divided gas, substantially as deat a surface of a mass of the material, introducing a reactlon-supporting gas at an other surface of the mass, conductlng the 'reaction-supporting gas through the mass,

' the mass, conducting the reaction-producing gas through the mass, propagating'the heat through the mass by internal reaction in one direction, and propagating a second reaction through the mass in another direction, substantially as described.

7. The process of treating finely divided material containing heat developing components, which comprises heating the upper surface of a mass of the material,- introducing a reaction-producing gas atthe lower surface of the mass, conducting the reactionproducing gas upward through the mass, propagating the heat downward through the mass by internal reaction, and propagating a second. reaction upward through the mass, substantially as described.

8. The process of treat-ing finely divided material containing gas forming components, which comprises heatinga surface of a mass of the material, introducing a reaction-producing gas at another surface of the mass, conducting the reaction-producing gas through the mass, propagating the heat through the mass by internal reaction in one direction, and propagating a second'reaction through the mass in another direction, substantially as described.

9. The process of treating finely divided material containing gas forming components, which comprises heating the upper surface of a mass of the material, introducing a reaction-producing gas at the lower surface of the mass, conducting the reactionproduclng gas upward through the mass,

propagating the heat downward through the mass by internal reactlon, and propagating a second reactlon upward through the mass, substantially as described.

10. The process of treating finely divided material containing combustible components, which comprises heating a surface of a mass of the material, introducing a combustion-supporting gas at another surface of the mass, conducting the combustionsupporting gas through the mass, propagating the heat through the mass by internal combustion in one direction, and propagating a second reaction through the mass in another direction, substantially as described.

11. The process of treating finely divided material containing combustible components, which comprises heating the upper surface of" a mass of the material, introducing a combustion-supporting gas at the lower surface of the mass, conducting the combustion-supporting gas upward through the mass, propagating the'heat downward through the mass by internal combustion, and propagating a second reaction upward through the mass, substantially as described.

12. The process of treating finely divided material containing carbonaceous components, which comprises heating a surface of a mass of-the material, introducing a coinbustion-supporting gas at another surface of the mass, conducting the combustion-supporting gas through the mass, propagating the heat through the mass by internal combustion in one direction, and propagating a second reaction through the mass'in another direction, substantially as described.

"13. The process of treating finely divided material containing carbonaceous components, which comprises heating the upper surface of a massof the material, introducing a combustion-supporting gas at the lower surface of the mass, conducting the combustion-supporting gas upward through the mass, propagating the heat downward through. the mass by internal combustion, and propagating a second reaction upward through the mass, substantially as described.

14;. The process of treating finely divided material containing combustible components, which comprises producing ignition in a mass of the material, feeding a gas current through the mass, causing a backward propagation of the plane of ignition against the flow of the gas current by means of a reaction internal to the mass, and propagating a clinkering reaction forward with the flow of the gas current, substantially as described.

15. The process of treating finely divided ,unaterial containing heat developing components, which comprises transmitting heat from a bodyof hot gases to a surface of a mass of the material, introducing a reaction producing gas at another surface of the mass, conducting the reaction-producing gas through the mass, propagating the heat through the mass by internal reaction 'in one direction, and propagating a second reaction through the mass in another direction, substantially as described.

16. The process of treating finely divided material containing heat developing components, which comprises transmitting heat from'a body of hot gases to the upper sur face of a mass of the material, introducing a reaction-producing gas at the lower surface of the mass, conductlng the reactionproducing gas upward through the mass,

propagating the heat downward through.

the mass by internal reaction, and propagating a second reaction upward through the mass, substantially as described.

17 The process of treating finely divided material containing gas forming components, which comprises transmitting heat from a body of hot gases to a surface of a mass of the material, introducing a reactionproducing gas at another surface of the mass, conducting the reaction-producing gas through the mass, propagating the heat through the mass by internal reaction in one direction, and propagating a second reaction through the mass in another direction, substantially as described.

. 18. The process of treating finely divided material containing gas forming components, which comprises transmitting heat from a body of hot gases to the upper surface of a mass of the material, introducing a reaction-producing gas at the lower surface of, the mass, conducting the reactionproducing gas upward through the mass, propagating the heat downward through the mass by internal reaction, and propagat-' ing a second reaction upward through the mass, substantially as described.

' 19. The process of treating finely divided material containing combustible components, which comprises transmitting heat from a body of hot gases to a surface of a mass of the material, introducing a combustion-supporting gas at another surface! of the mass, conducting the combustion-supporting gas through the mass, propagating the heat through the mass by internal combustion in one direction. and propagating a second reaction through the mass in another direction, substantially as described.

20. The process of treating finely divided material containing combustible components, which comprises transmitting heat from a body of hot gases to the upper surface of a mass of the material, introducing a combustionsupporting gas at the lower surface of the mass, conducting the combustion-supporting gas upward through the mass, propagating the heat downward throilgh the mass by internal combustion,

and propagating a second reaction upward" through the mass, substantially as described. 21. The process of treating finely divided material containing combustible components, which comprises transmitting heat 22. The process of treating finely divided ing a clinkering reaction upward through the movable mass, substantially as described.

23. The process of treating finely divided material containing carbonaceous components, which comprises transmitting heat from a. body of hot gases to the upper surface of a mass of the material, introducing I a combustion-supporting gas at the lower surface of the mass, conducting the combus tion-supporting gas upward through the mass, propagating the heat downward through the mass by internal combustion, and propagating'a clinkering reacticn'u y ward through the mass, substantially as described.

24;. The process of treating finely divided material containing carbonaceous components, which comprises transmitting heat from abody of hot gases to the upper surface of a mov'able mass of the material, in-

. troducing a .combustion-supporting gas at the lower surface of the movable mass, conducting the combustlon-supportmg gas upward through the movable mass, propagat ing the heat downward through the movable mass by internal combustion, and propagating a clinkering reaction upward through the movable mass, substantially as described.

25.. The process of treating finely divided material containing combustion-supporting and other components, which comprises transmitting heat from a body ofhot gases to the upper surface of a mass of the mate- 'rial, introducing a gas (which is reactive with some of the components of the material) at the lower surface of the mass, conducting the reactive gas upward through the mass, propagating the heat downward through the mass by internal combustion, and propagating a second reaction upward through the mass, substantially as described.

26. The process of treating finely divided metal-bearing material containing combustible components, which comprises transmitting heat from a body of hot gases to the upper surface of a mass of the material, introducing a COmbUStJOIl-SUPIJOI'tlllg gas at the lower surface of the mass, conducting the combustion-supportinggas upward through the mass, propagating-the heat downward through the mass by internal combustion, and propagating-a clinkering reaction upward through the mass, substantially as described;

27. Thepro'cess of treating finely divided ble components, which comprises transmit ting heat' from a body of hot gases to the upper surface of a movable mass of the material, mtroducmg a combustion-supporting gasat the lower-surface of the movable mass, conducting. the combustion supportmg gas upward through the -movable mass, propagating the heat downward through the movable mass vby internal combustion, and

propagating a clinkering reaction upward I through the movable mass, substantially as described. 1 r

28. The process of treating finely divided metal-bearing material containing carbonaceous components, which comprises transmitt-ing heat from a body of hotgases to the upper surface of a mass of the material, introducing a combustion-supporting gas at" the lower surface of the mass, conducting thecombustion-supporting gas upward through the mass, propagating the heat downward through the mass by internal combustion, and propagating a clinkering reaction upward through the mass, substantially as described.

29. The process of treating finely divided metal-bearing material containing carbonaceous components, which comprises transmitting heat from a body of hot gases to the upper surface of a movable mass of the material, introducing a combustion-supporting gas at the lower surface of the movable mass, conducting the combustion-supporting gas upward through the movable mass, propagating the heat downward through the movable mass by internal combustion, and propagating a clinkering reaction upward through the movable mass, substantially as described.

30. The process .oftreating a finely divided oxid-ore mixture containing combustible components, which comprises transmitting heat from a body of hot gases to the upper surface of a mass of the mixture, introducing a combustion-supporting gas at the lower surface of the mass, conducting the combustion-supporting gas upward through the mass, propagating the heat downward through the mass by internal combustion,

and propagating a clinkering reaction up-.

ward through the mass, substantially as dej scribed.

31. The process of treating a finely divided oxid-ore mixture containing combustible components, which comprises transmitting heat from a body of hot gases to the upper surface of a movable mass of the mixture, introducing a combustionsupporting. gas at the lower surface of the movable mass, conducting the combustion-supporting. gas upward through the movable mass, propagating the heat downward through the movable mass by-internal combustion,- and I propagating a clinkering reaction upward through the movable mass, substantially as described.

32. The process of treating a finely divided oxid-ore mixture containing carbonaceous components, which comprises transmitting heat from abody of hot gases to the lower surface of a mass of the mixture, in- .troducmg a combust on-supporting gas at the lower surface of the mass, conductin the combustion-supporting gas upwar through the mass, propagating the heat downward through the mass by internal combustion, and propagating a clinkering reaction upward through the mass, substantially as described. p

' 33. The process of treating a finely divided oxid -ore mixture containing carbonaceous components, which comprises transmittingheat from a body of hot gases to the upper surface ofa movable mass of the mix-- ture, introducing a combustion-supporting gas at the lower surface of the movable mass, conducting the combustion-supporting gas upward through the movable mass, propagating the heat downward-through the movable mass by internal combustion, and propagating a clinkering reaction upward through the movable mass, substantially as described.

34. The process of continuously treating finely divided material containing combustible components, which comprises continuously feeding the material-to the moving perforated hearth of a reverberatory fur nace to form a moving mass of .the material, continuously transmitting heat from a body of hot gases to the upper surface'of the moving mass, continuously introducing a' combustion-supporting gas at the lower surface of the moving mass, continuously conducting the combustion-supporting gas upward through the "movingjmass, continuously propagating the heat downward through the moving massifn one part of the .furnace by internal combustion, 'a'nd'continuously propagating a clinkering reaction upward only throu h the moving mass in another part of the furnace, substantially as described. v

35. The process of continuously treating finely divided material containing carbonaceous components, which comprises continuously feeding the material to the moving perforated hearth of a reverberatory furnace to form a moving mass of the material,

continuously transmitting-heat from a-body of hot gases to the upper surface ofthe moving mass, continuously introducing a combustion-supporting gas at the lower surface; of the movlng mass,- continuously conduct-' ing the combustion-supporting gas upward through the moving mass, continuously propagating the heat downward through the moving mass in one part of the furnace by internal. combustion. and continuously props t 38. The

agating a clinkering reaction upward only through the moving mass in another partof the furnace, substantially as described.

36. The process ofcont-inuously treating finely divided metal-bearing material containing combustible components, which comprises continuously feeding the material to the moving perforated hearth of a reverberatory furnace to form a moving mass of the material, continuously transmitting heat from a body of hot gases to the upper sur-.

.face of the moving mass, continuously introducing a combustlon-supporting gas at the lower surface of.t he moving mass, contin-. uously conducting the combustion-support ing gas upward throu h the moving mass,

continuously propagatmg the'heat downward throughthe moving mass m' one part of the furnace by internalcombustiori, and

"continuously propagating a clinkering reactionupward only through the moving mass in another part of the *furnace,fsubstantially as described.

37. 'The rocess of continuously treating finely divi ed metal-bearing material con-.

taining carbonaceous components,-: which comprises continuously feedlng the material to t e movingperforated hearth f a re 'verberatory furnace to form a moving mass 'of the material, continuously transmittingheat from a body of hot gases to the upper surface of the moving mass, continuously introducing a combustion-supporting gas at the lower surface. of the movin mass, continuously conducting the com ustion-supporting gas up'war through the moving mass, continuously propagating. the heat downward through the moving mass in one part of the furnace byinternal combustion, and continuously propagating a clinkering reaction upward only through the moving mass'in another part of the furnace, substantially as described.

, rocess of continuously treating a finely dlvldd oxld-ore mixture containing part of the furnace by internal combustion, I

and continuously propagating a clinkering reaction upward only through the moving mass in another part of the furnace, substantially as described.

39. The process of continuouslytreating a finely divided oxid-ore mixture containing carbonaceous components, -which comprises continuously feeding the mixture to the moving perforated hearth of a reverbera tory furnace to form a moving mass of the mixture, continuously transmitting heat from a body of hot gases to the upper surface of the moving mass, continuously in troducing a coinbjustion-supporting gas at the,

lower surface of the moving mass, continuously conducting the combustion-supporting gas upward through the moving mass, continuously propagating the heat downward through the moving mass in one part of the furnace by internal combustion, and continuously propagating a elinkering reaction upward only through the moving mass in another part of the furnace, substantially as described. l

4.0. The process of continuously treating finely divided iron oXid, which comprises mixing with the iron oxid finely divided fuel to form a mixture capable of being clinkered; continuously feeding the mixture to the moving perforated hearth of a reverberatory furnace to form a moving mass;

unaccompanied by a clinkering reaction, is-

caused to continuously propagate downward from the upper surface and through the moving mass in one part of th furnace, while a clinkering reaction initiated at the lower surface is caused to continuously propagate upward through the moving mass in another part of the furnace.

In testimony whereof, I afiix my signature in the presence of witnesses.

FREDERICK W. Yosr.

Witnesses: v

(Z. W. FOWLER, EDWARD, A. BERN.

Copies of this patent may be obtained ior five cents each, by addressing the Commissioner of Patents,

1 Washington, D. G. 

